Yes we have a plan to update heroes with a tree like structure. Plan is also to introduce new heroes with new abilities like magic when we do. But the current version that we are working on 0.91 wont see those changes. We are trying to keep this one smaller to be able to release something more often.
0.91 will mostly be less fun updates. Things like not reloading the page when you have a new turn. Useful vs AI and in realtime games that few people play
. The most fun feature of 0.91 is replays.
I'm writing down these ideas. I think a healing bonus is a good idea, and giving it to the paladin seems like a good idea.